Tutorial on Upgrading of Oilsands Bitumen Murray R Gray Imperial Oil/NSERC Industrial Research Chair in Oil Sands Upgrading Department of Chemical and Materials Engineering University of Alberta
What is Oilsands Bitumen? Heavy crude oil extracted from oilsands High viscosity, high sulfur oils Major production from mining near Fort McMurray, Alberta Also produced at Cold Lake and Peace River
Why Upgrade Bitumen? Oil refineries are designed for lighter crudes (density < 950 kg/m 3 ) Bitumen has density over 1000 kg/m 3, over 4% sulfur, viscosity 1000x light crude oil Needs upgrading to sell to most refineries
Bitumen and Heavy Oil Upgrading Upgrading: any fractionation or chemical treatment of bitumen or heavy oil to increase its value Minimum objective: reduce the viscosity to allow shipment by pipeline without adding a solvent Maximum objective: process to give a crude oil substitute of high quality (a synthetic crude oil )
Bitumen and Heavy Oil Upgrading Minimum upgrading approach Reduce viscosity and control solids and water None in operation; research underway on simple, small scale processes Full upgrading approach Reduce sulfur and maximize distillable oil Large expensive plants much like refineries Focus on oil components that are too heavy to distill (boiling point over 524 C)
Bitumen Properties Up to 1/2 of the bitumen can be recovered by distillation under a vacuum The residue contains large molecules, with molecular weights over 400 Complex mixture of chemical species, including aromatics, substituted aromatics, organic sulfur and nitrogen compounds
Sulfur, Nitrogen and Metals in Residue Fraction of Feeds Sulfur, wt% Nitrogen, wt% Athabasca 5.14 0.56 Cold Lake 5.10 0.45 Lloydminster 4.69 0.53 Peace River 7.02 0.63 Metals, ppm Nickel Vanadium Athabasca 150 290 Cold Lake 200 490 Lloydminster 140 190 Peace River 130 410
Asphaltenes in Bitumen Dilution of Alberta bitumens in n-pentane or n-heptane gives 10-20% of brown/black solid precipitate This fraction is called asphaltene, contains highest molecular weight (up to 5000) and most polar components in the oil Asphaltenes are very reactive during processing
Asphaltene molecules Based on Sheremata et al., 2004; Strausz 1999 O N N V O N N N V N O N N S S HN S O O O N H N O S S
Upgrading Steps Large molecules that will not distill (called Residue ) must be cracked to give lighter molecules Cracking takes place in the primary upgrading step at over 400 C Cracking products rich in sulfur and nitrogen, so secondary upgrading is required to get sulfur below 0.5%
General Upgrading Scheme Sour Medium Crudes Bitumen Feed Separation -Desalting - Distillation - Deasphalting Primary Upgrading (Vacuum Residue Conversion) - Thermal cracking - Coking - Hydroconversion Secondary Upgrading - Hydrotreating - Hydrocracking Sweet Light Crudes Heavy By-Product* Natural Gas Utilities - Hydrogen - Steam - Power Environmental Controls - Sulfur removal and conversion - Sour water Sulfur By-Products Waste Heat * Heavy By-Product = Coke, Asphaltenes, or Vacuum Residue Extraction Upgrading Section F4 Slide 11
Upgrading Technologies Bitumen Upgrading Separations Reactions Distillation Asphaltene and solids removal Ultra Low T <100 o C Low T 100-350 o C Moderate T 350-470 o C High T > 470oC Bioupgrading In situ catalysis Liquid Phase Low/No Coke Vapor+Liquid Coking Commercial technology Under development
Suncor Base Plant and Millennium Sweet fuel gas Diluent Amine Unit/ Sour Water Stripper Air H 2 S + NH 3 Sulfur Unit Sour streams/h 2 Purge Sulfur Diluted Bitumen Diluent Recovery Bitumen Delayed Cokers Coke Coker Distillates Naphtha Kerosene and Gas Oil Hydrotreaters Vacuum Unit Vacuum Residue Hydrotreated Distillates Gas Oil Kerosene Side draw Storage to Pipeline Natural Gas Hydrogen Plant Hydrogen Sweet/Sour Blends, Diesel Upgrading Section F4 Slide 13
Shell Upgrader
Long Lake Upgrader Diluted Bitumen Atmospheric and Vacuum Distillation Gas Oil Hydrotreater + Hydrocracker Naphtha to SAGD Sweet Crude Oil H 2 H 2 S Sulfur Plant Sulfur Deasphalter Asphalt Deasphalted oil Gasifier Syngas to SAGD Steam Generators Thermal Cracking Oxygen Upgrading Section F4 Slide 15
Asphaltene Separations Asphaltene and Solids Removal In situ VAPEX Solvent Deasphalting (Pumpable product) Paraffinic Froth Treatment (Aqueous slurry product) Supercritical Extraction (Powder product) Mixed Solvents for Selective Separation ROSE Process Low Temperature Pressurized Operation SELEX-Asp Commercial technology Under development
Solvent Deasphalting Precipitate asphaltenes using paraffinic solvents (propane to hexane; C 3 -C 6 ) Solvent:oil ratio is 4:1 or higher - more solvent gives cleaner separation Major utility cost is solvent recovery Separation of oil and solvent is easy above T c of solvent, minimizing energy costs Nexen Long Lake only oilsands example
Moderate Temperature Processes Moderate T Liquid Phase Visbreaking <25% Conversion Catalytic Hydroconversion Solvent Cracking Aquaconversion (Catalytic) Supported Ni/ Mo Catalysts (50-80% conversion) Slurry Catalysts >70% Conversion Supercritical Water LC Fining H-Oil Commercial technology ENI Slurry Technology (Recycle Mo catalyst) Under development
High Temperature Processes
Processes for Primary Upgrading Residue FCC Hydroprocessing Thermal cracking Coking Deasphalting North America + Venezuela, 1998
Thermal Conversion Thermal cracking underlies all current commercial reactor technology Rely on hydrogen gas to stabilize products
Process Characteristics - Coking Low pressure, reliable, safe process Low operating costs Low liquid product yields Coke by product is rich in sulfur, so this material is stockpiled in mines Main process for CNRL, Suncor and Syncrude
A Coke Primer coke (kok) noun A solid residue left after incomplete combustion of petroleum etc. Probably from Northern English dialect colk, core, of unknown origin
Thermal Cracking Reactions Breaking a C-C bonds required to get significant upgrading Two types of products - one stable and one unsaturated and unstable (alkenes) Use catalytic hydrotreating to stabilize the unsaturated products
Coking Technologies Delayed coking - liquid feed cracks in a large drum, and coke accumulates at the bottom with time (CNRL and Suncor) Fluid coking - liquid feed is sprayed into a bed of hot coke particles (Syncrude)
Hydrogen Addition Processes Hydroconversion or Hydroprocessing Combine some catalytic activity with thermal cracking Hydrotreating Catalytic sulfur and nitrogen removal Minimal cracking Hydrocracking Gasoline production using a bifunctional catalyst
Hydroconversion Used by Husky, Shell, and Syncrude for primary upgrading Feed cracks in the presence of hydrogen and a supported-metal catalyst (Mo + Ni on aluminum oxide) Hydrogen suppresses coke, helps remove sulfur
Hydrotreating Lower temperature process, with a similar catalyst (nickel + molybdenum on a support of aluminum oxide) High level (>90%) removal of sulfur, >70% removal of nitrogen Negligible cracking
Hydrocracking High pressure catalytic process used by refineries (Shell Scotford, Suncor Edmonton) to convert heavy distillates into feeds for gasoline Catalyst gives both cracking (e.g. zeolite) and hydrogenation activity Higher hydrogen pressure than hydroconversion or hydrotreating